Auto merge of #85993 - bjorn3:serde_json, r=wesleywiser

Remove all json handling from rustc_serialize

Json is now handled using serde_json. Where appropriate I have replaced json usage with binary serialization (rmeta files) or manual string formatting (emcc linker arg generation).

This allowed for removing and simplifying a lot of code, which hopefully results in faster serialization/deserialization and faster compiles of rustc itself.

Where sensible we now use serde. Metadata and incr cache serialization keeps using a heavily modified (compared to crates.io) rustc-serialize version that in the future could probably be extended with zero-copy deserialization or other perf tricks that serde can't support due to supporting more than one serialization format.

Note that I had to remove `-Zast-json` and `-Zast-json-noexpand` as the relevant AST types don't implement `serde::Serialize`.

Fixes #40177

See also https://github.com/rust-lang/compiler-team/issues/418

1 files changed, 0 insertions, 2 deletions

diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 1327bf6fcd4..a178cca6d10 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -644,8 +644,6 @@ fn test_debugging_options_tracking_hash() {
     // Make sure that changing an [UNTRACKED] option leaves the hash unchanged.
     // This list is in alphabetical order.
     untracked!(assert_incr_state, Some(String::from("loaded")));
-    untracked!(ast_json, true);
-    untracked!(ast_json_noexpand, true);
     untracked!(borrowck, String::from("other"));
     untracked!(deduplicate_diagnostics, false);
     untracked!(dep_tasks, true);